What decentralized applications are actually solving problems effectively?

[Ava.T]

I'm building decentralized applications solving problems and I want to learn from what's working. What decentralized applications solving problems have you used that actually provide value? I'm not talking about DeFi yield farming or NFT marketplaces necessarily, but applications that solve real-world problems like supply chain tracking, credential verification, or data privacy. How are these decentralized applications solving problems better than traditional solutions?